1. Field of the Invention
The present invention relates to a bicycle freewheel hub, more particularly to a bicycle freewheel hub which is easy to assemble and which provides an enhanced transmission effect.
2. Description of the Related Art
FIG. 1 illustrates a conventional bicycle freewheel hub which includes a shaft 2, and a tubular hub shell 1 sleeved rotatably on the shaft 2 and having a first end formed with a ball recess 1b and a second end opposite to the first end. A first bearing assembly is received in the ball recess 1b and is disposed around the shaft 2. The first bearing assembly includes a ball casing 1c, a ball seat 1d, a securing member 1e and a nut 1f. A positioning seat 3a is sleeved rotatably on the shaft 2, and has a first end fixed to the second end of the hub shell 1. A tubular driving member 3c is disposed around the positioning seat 3a. As shown in FIG. 2, the positioning seat 3a has an outer periphery formed with two opposite radial indentions 3a', each of which is provided with a clutch member 3b and a spring member 3d for biasing the clutch member 3b radially outward. The driving member 3c has an inner surface confronting the outer periphery of the positioning seat 3a and formed with a plurality of ratchet teeth 3c' for engaging the clutch members 3b. A second bearing assembly is received in the driving member 3c and is disposed around the shaft 2. The second bearing assembly includes ball seats 3e, 3e', a securing member 3f, a tubular member 3g and a nut 3h.
When the driving member 3c is rotated in a first direction to advance a bicycle, the ratchet teeth 3c' of the driving member 3c engage the clutch members 3b of the positioning seat 3a to result in rotation of the positioning seat 3a together with the driving member 3c, thereby causing corresponding rotation of the hub shell 1. When the driving member 3c is rotated in a second direction opposite to the first direction, the ratchet teeth 3c' are disengaged from the clutch members 3b to result in idle rotation of the driving member 3c relative to the positioning seat 3a and the hub shell 10.
Although the conventional bicycle freewheel hub achieves the desired transmission effect, it suffers from the following drawbacks:
Since only two clutch members 3b are provided for coupling the driving member 3c to the positioning seat 3a when the driving member 3c is rotated in the first direction, the resulting coupling effect is not satisfactory. In case one of the clutch members 3b is damaged, the coupling effect would be affected significantly. Moreover, the clutch members 3b and the spring members 3d must be mounted on the radial indentions 3a' of the positioning seat 3a when manufacturing the positioning seat 3a. In assembly, the clutch members 3b must be forced inwardly so that the positioning seat 3a can be placed within the driving member 3c. Inconveniences thus result during manufacturing and assembly of the conventional bicycle freewheel hub.